Unauthorized removal or actual theft of merchandise from a display counter or the like has been an aggravating and long-time problem particularly for retail stores and merchants who display small but valuable items of merchandise in such a manner that the buying public is allowed to handle or try out the merchandise. Such merchandise is generally small and easily movable and may consist of small radios, electrical appliances and tools of all kinds, various forms of electronic equipment and more valuable items such as jewelry. Such goods may be easily removed by unscrupulous persons, especially when the premises are crowded and the sales personnel are too busy to watch every item. This problem of proper protection is particularly magnified for dealers in antique firearms and other weapons which are generally displayed on open tables usually in congested and crowded environments such as would be encountered in antique shows and flea markets. A potential buyer of an antique firearm, for example, would want to handle and examine closely the firearm prior to any purchase. While desiring to afford such purchasers every opportunity to examine goods, the dealer at the same time finds it difficult to adequately safeguard and watch all of his merchandise, particularly under the crowded conditions described above.
Various forms of electrical alarm devices have been proposed wherein a long electric wire is looped through a portion of the merchandise and made a part of an alarm system so that if the wire is cut or broken in order to remove the goods an alarm is sounded. Such loop segments can be made at virtually any required lengths so as to permit handling of the goods for normal customer inspection without danger of inadvertently actuating any alarm system. Such systems are generally in the form of a continuity circuit so that severing of the cable would actuate the alarm. The principal difficulty with such systems is that they can be defeated by a "jumper" wire clipped to each side of an intended cut of the conductor.
In U.S. Pat. No. 3,972,039 it has been proposed to overcome the effects of a "jumper" by providing a further wire in the two wire conductor connected to the protected article. This further wire is twisted with the other two wires and produces an alarm when shorted to one of the other wires. This proposal requires that an electrical connection be made between the third wire and the other two wires in the conductor in order to transmit an alarm. However, the twisted wires would cause false triggering of the system due to the inductive effect of the twisted wires picking up static and R.F. fields. While this patent states that unauthorized use of a test meter would actuate the alarm, this is not true today since present state of the art digital test equipment does not draw any current from the system. Thus, this prior art system would not be effective in today's market.
It is therefore the principal object of the present invention to provide a novel and improved electrical security system for individual articles on display.
It is another object of the present invention to provide such a security system wherein each article is connected by a sensor detector cable to an alarm system which is actuated by any attempts to cut the cable or interfere physically in any way with the cable.
It is a further object of the present invention to provide such a security system wherein the sensor detector cable includes both a continuity circuit and a floating circuit. It is an additional object of the present invention to provide such an electrical security system which is dependable in operation, simple and inexpensive to install and operate, and capable of indicating any attempts to remove an article without interfering with customer inspection of the article.